Recently it has been indicated that there is a correlation between decrease in quantity of ingestion of fibers due to the tendency of increased uptake of highly refined foods and increase of various symptoms or diseases such as constipation, irregularity of defecation, disturbance of intestinal flora, carcinoma of colon, hypertension, diabetes mellitus and others. For this reason, it is recommended to take much more quantity of dietary fibers.
Konnyaku is a kind of plant belonging to the family of Araceae (Amorphophallus konjac) and have been cultivated in Japan, China and other Asian countries, and Konnyaku powder is prepared by drying smashed tubers of Amorphophallus konjac. Konnyaku powder is sold in the market as the ingredient for a traditional food called konnyaku (devil's tongue: a paste made from the polysaccharides prepared from tubers of Amorphophallus konjac). Konnyaku powder has been utilized as water soluble dietary fibers or a material for preparation of natureal food of low-calorie, since it contains glucomannan, in a high concentration up to about 80% (by weighte, which comprises water-soluble polysaccharides and is hardly digestible in human intestine (cf. "Chemistry of polysaccharide" page 280, 1955, Kyohritsu Shuppan Kabushiki Kaishae.
More particularly, it has been reported that when Konnyaku powder is ingested, the dietary fibers thereof may reach to the large intestine without being subjected to digestion in the small intestine, and they are excreted. It has been also reported that cholesterol, derived from foods and bile acid, is absorbed in Konnyaku powder and coincidently excreted. Thus Konnyaku is powder effective to decrease serum cholesterol level. Moreovr, Konnyaku powder is effective to adjust intestinal functions or maintain the good intestinal conditions and to manifest growth promoting activity of Bifidobacteria (Kiriyama et al, Journal of Nutrition, Vol. 97, page 382, 1968; Mizutani et al, "Intestinal Flora and Nutrition", page 89, 1983, Gakukai Shuppan Center).
Also it is reported that the dietary fibers in Konnyaku powder may swell in its aqueous solution to hold a surprisingly huge quantity of water amounting to hundreds times of itself and that when the dietary fibers are ingested, they give rise to perception of satiety since they reside for a prolonged period in the stomach and they reside for a short time in the intestine, thus they are useful as a natural ingredient of a low-calorie food for prevention from corpulence or obesity (Innan et al, "dietary fibers", pages 73 and 76, 1982, Daiichi Shuppan)
It is also reported that oligosaccharides mainly in the range of disaccharides to hexasaccharides, which are prepared from hydrolysis of Konnyaku powder, are effective to promote growth of intestinal Bifidobacteria (Unexaminded Patent Application Gazzette No. 58-212780).